Comprehensive analysis of power plants with a high-enthalpy storage device

To address the intermittency of renewable energy and the associated risks to grid stability, this study proposes a thermal energy storage system to improve the load response flexibility of coal-fired power plants across a wide load range. Using a 1000 MW unit as a reference case, the system integrates a high-enthalpy working medium with regenerative steam extraction throttling. The thermodynamic analysis showed notable improvements: power output increased by 14.16 MW (7.08%), with a coal consumption reduction of 22.65 gce/kWh at 20% of rated load. Operational duration of the thermal energy storage system varied with pressure, lasting 37 minutes at 6 MPa/20% of rated load compared to 5.9 minutes under the full-load condition at equivalent pressure. The techno-economic analysis established 6 MPa/30% of rated load as the optimal configuration, offering a payback period of 5.7 years, significantly shorter than the 34.8 years at 2.5 MPa/rated load. The thermal energy storage system requires no modifications to the boiler and operates efficiently with low thermodynamic parameter steam while maintaining stable steam temperatures. These results provide practical guidance for retrofitting conventional coal-fired units into flexible load-rising regulation, which is particularly valuable for power systems with high renewable energy penetration.